KR102434124B1 - Hot runner device with overload protection - Google Patents

Abstract

The invention comprises at least one needle valve nozzle (1) and a shut-off needle (3) movable by means of a moving means in the needle valve nozzle (1), and has an overload protection device for the shut-off needle (3), The overload protection device is embodied as follows: the shut-off needle is connected directly or indirectly to the moving means in at least one first direction of movement by way of at least one frictional connection 21 which can be released if the critical force is exceeded. It relates to a hot runner device.

Description

Hot runner device with overload protection

The invention relates to a hot runner device comprising an overload protection device for a shut-off needle according to the preamble of claim 1 .

It is known to provide a hot runner device comprising an overload protection device having a positive connection or breakage mechanism, which, in case of overload by the power flow of the drive device, a movable shut-off needle of the hot runner during the closing operation can be stopped to prevent damage to the blocking needle. However, the known overload protection devices are structurally designed in a relatively complex manner, but can only provide limited functional reliability. Reference is made, for example, to DE 10 2015 216 059, which shows a known overload device which exhibits positive engagement in such a way that it engages with radially movable ball bodies as an overload protection device, , where the relatively long travel of the shut-off needle must be covered to trigger or activate this overload protection device. If the shut-off needle becomes clogged while opening or closing and the distance is not sufficient to activate the overload protection device, the shut-off needle may be damaged or moved to an unauthorized position without notice.

An object of the present invention is to solve the above problems. A hot runner device with a simple design and reliable overload protection should be created.

The present invention can achieve this object by the content of claim 1. Advantageous embodiments may be given in the dependent claims.
According to claim 1, there is provided: the hot runner device has at least one needle valve nozzle and movable means within the needle valve nozzle (preferably only in one direction forward and backward) Having a shut-off needle and an overload protection device for the shut-off needle, the overload protection device is embodied as follows: The shut-off needle has a frictional connection that is releasable when a limit force is exceeded. ) connected directly or indirectly to the moving means in at least one first direction of movement.
The protective mechanism for overload protection in this case is previously known, since it has been found that the triggering limit force with which the overload protection device releases the shut-off needle can simply be adjusted in a relatively precise manner via a friction connection. As with the proposed solution, it is advantageous not through a positive connection or a fracture mechanism, but preferably only through a friction connection. In addition, the friction connection can be realized by simple design means with small space requirements. This will be described below in more detail with reference to preferred embodiments and the dependent claims, but the present invention is not limited thereto. In the case of the present invention, the triggering path preferably approaches quasi zero or approaches to a substantially relevant extent.
According to an alternative embodiment, each advantageously embodied and possibly coupled, the friction connection is on the one hand a retractable, stretchable and/or stretch-shrink assembly and/or on the other hand a self-contained assembly. - Implemented through self-locking. Both principles form an advantageous embodiment and a further development of the subject matter of claim 1 which works well.
Since the trigger limiting force in this way can be adjusted particularly well, the overload protection device can be provided by a preferred variant based solely on the friction principle.
According to one variant, only one single friction connection is provided, which when exceeding the trigger limiting force, for example closing the outlet opening of the needle valve nozzle with a shut-off needle, only one causes release of the blocking needle in a single direction of movement of However, the shut-off needles for opening or closing the outlet opening of the needle valve nozzle in two different directions of movement - particularly in opposite directions - are limited in order to effectively protect the needle valve nozzle from damage in both the open actuation and the close actuation. It may also be provided for direct or indirect connection to the moving means by means of at least one frictional connection which can be disengaged when a force is exceeded.
Structurally, the present invention according to one variant by way of example - also advantageously one or two releasable friction connections as a releasable self-locking cone press-fit connection Alternatively, it can be implemented in each case via two detachable cone press-fit connections.
The first releasable cone press-fit connection comprises an inner cone in the junction of an outer cone on the valve needle and a corresponding moving means or shut-off needle, in particular a pin as first friction partner, an inner cone as second friction partner It can be provided according to a modification that can be realized in a structurally simple method implemented with a sleeve having a , and another sleeve in the moving means.
According to a further structurally advantageous variant, in particular for realizing a second cone press-fit connection, as first friction partner an outer cone on the sleeve pierced by the shut-off needle and as second friction partner a moving means or a moving means It may be provided that is formed as an inner cone on an additional sleeve inserted therein.
It is preferred that the shut-off needle can be driven back and forth linearly exclusively with the moving means. It can also be advantageously provided that the blocking needles are connected in this direction and/or in an opposite direction or that these directions are only frictionally coupled with the moving means. According to one variant, the frictional engagement is also the positive connection of one part (blocking needle or blocking needle) which engages in the corresponding circumferential groove of the other part (moving means or blocking needle), for example by way of latching. can be supplemented by small circumferential grooves in the moving means). However, the trigger force is preferably determined substantially by friction engagement, ie at least 50% determined by friction engagement.
In this case, one or both of the friction and self-locking connections are in the axial direction such that the blocking needle or the abutment of the blocking needle is connected to the moving means in a frictional engagement and self-locking manner so that the blocking needle exceeds the self-locking and is greater than the static friction of the friction connection. Provided to automatically disengage upon introduction of force.
An embodiment is also advantageously implemented, since, in particular, an axial displacement of the shut-off needle with respect to the moving means does not occur before the overload is reached, since a frictional engagement is selected that does not allow any elastic deformation upon release. can be
According to one variant, it is also advantageous if the restraining force is smaller than the exhausted mounting force (for pressing the shut-off needle into the moving means). It is also advantageous to set the level of the restraining force according to the level of the mounting force. Preferably, the setting of the constraining force is additionally effected in a simple manner via the mounting force.
Finally, with respect to an embodiment of the invention formed as a shrink assembly, the shrink assembly is a cylindrical retractable, for example, a heated sleeve being retracted by cooling to the cylindrical portion of the shut-off needle, in particular the driving end. It may be provided to be designed as an assembly.
In connection with embodiments of the present invention as a stretch assembly, the stretch assembly may be formed into a cylindrical stretch assembly that expands in a cylindrical portion, sleeve or receptacle, for example as a cooled shut-off needle is heated to ambient temperature. can be provided.
According to a variant, it is also advantageously possible to combine the retractable assembly and the elongate assembly to form a stretch-deflate assembly. Assemblies formed by heating and/or cooling are also called cross-press assemblies.
Preferably, the overload protection device may have a sensor that detects the triggering of the overload protection device and transmits a signal to the controller of the injection molding machine.
Overall, it is advantageous that the protection mechanism for overload protection takes place via a friction connection rather than a positive connection or break mechanism, as in known solutions, so that the trigger force is easily adjustable, and the trigger is In one case, no transformation occurs or occurs directly without the need to cover the reaction pathway.

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BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below with reference to embodiments shown in the drawings:
1 a), b) and c) each show a cross-section through a portion of a hot runner device; Parts a), b and d) of the figure on the one hand and a), c) and d) on the other hand represent two different operating states of the hot runner device in each case in a hypothetical juxtaposed state;
Fig. 2a) is an enlarged cross-sectional view of the components of the hot runner device of Fig. 1b) in an overload-free operating state, and b) shows the components of a) after the occurrence of a first overload situation;
3 a) is a cross-sectional view of a component of a first variant of the hot runner device of the type of FIG. 1 in a first operating state without overload, and in b) after the occurrence of the first overload situation (movement in the positive X direction) shows the components of a) of a) of overload;
In Fig. 4a), it is a component of the first variant of the hot runner device according to Fig. 3a) in a second operating state without overload, and in b) after the occurrence of another overload situation (overload during movement in the negative X direction) a) shows the components of a);
In Fig. 5 a), the components of another embodiment - structurally simple - according to the principle of Fig. 2, b) the structure of another embodiment in which the needle head according to the principle of Figs. 3 and 4 is formed in a conical shape elements and c) show the components of a structurally very simply constructed embodiment in which the head of the needle according to the principles of FIGS. 3 and 4 is formed cylindrically and the conical pin forms the junction of the needles;
6 a) and b) a simplified cross-sectional view of a variant of the hot runner device of the type of FIG. 1 in an assembled state of a self-locking component with description of the angles and vectors of force to account for the effective mounting force shows the components of a) together with the description of the force vectors and angles to account for the action force after the occurrence of the first overload situation;
FIG. 7 shows a diagram of the force ratio between the release force/mounting force as a function parameterized by the coefficient of friction μ of the self-locking cone connection according to FIGS. 2-5 and the lateral angle α of the cone in FIG. 6 , FIG. Structural embodiments are shown in simplified form.

Each of the terms above and below or right and left as used hereinafter relates to the position shown in the figure. The installation location may deviate from this, and thus the terminology should be understood relatively.
1 shows the interaction of parts a), b) and d) or parts a), c) and d), respectively, in cross-sectional views of a part of a hot runner device with a needle valve nozzle 1 . This device is designed for injection molded plastic components. The plastic component is injection molded in a mold, here as a mold plate with an opening, denoted only by the line S and not otherwise shown (see for example DE 10 2015216 059 A1), mainly with a gate bore bore) with a mold plate.
Here, Fig. 1 is divided into four parts spaced apart from each other for simplicity, and parts a), b) and d) in the virtual juxtaposition state show the hot runner device in the closed position, and in the virtual juxtaposition state. Parts a), c) and d) show the hot runner device in the open state.
The outlet end of the needle valve nozzle (1) aligned towards the mold plate can be closed in the closed position by the closed end (2) of the shut-off needle (3), so that the plastic from the needle valve nozzle (1) or into the mold can no longer be imported.
In FIG. 1b the shut-off needle 3 is moved along the direction of the mold (here, downward direction) so that the needle valve nozzle 1 is closed. On the other hand, in the open position of Fig. 1c, the shut-off needle is moved away from the mold (here, in an upward direction) so that the needle valve nozzle 1 is opened. In this state, the plastic may be introduced into the mold.
The needle valve nozzle 1 and the shut-off needle 3 have a main direction of extension X. The shut-off needle 3 moves in a restrictive manner when opening and closing the needle valve nozzle 1 with respect to it in the direction X and opposite to the direction X. The blocking needle 3 is for this purpose held at the driven-end away from the free end 2 (hereinafter also referred to as the driving end) 4 in the moving means of the lifting device. This moving means can be formed as a lifting plate 5 . The moving means can be moved in the X direction by means of the drive device 6 or is itself part of the drive device (eg a piston).
The moving means (here the lifting plate 5 ) moves back and forth in the stroke volume 33 of a hot runner injection mold having a plurality of plates 8 , 9 , 10 in the X direction relative thereto Possible, a hot runner portion 11 having hot runner flow elements 12 , 13 , 14 , 15 inside and outside these plates is formed. In the so-called distributor - the flow element 15 - a needle valve nozzle 1 is attached thereto.
The hot runner flow element 12 to 15 and the needle valve nozzle 1 each have a channel section, and these channel sections, by their interaction, the blocking end between the closed end of the needle valve 1 and the driving end 4 of the shut-off needle It opens into the annular space around the needle 3 and extends to the open outlet end of the needle valve nozzle 1, by moving the shut-off needle 3, the melt (melt) This mold plate (S) forms a melt guide channel (16), which can release or block the flow into it. A gap is formed between the hot runner elements 12 , 13 , 14 , 15 and the remainder of the tool 7 to separate the hot or warm area from the relatively cold area thereto. In order to keep the plastic melt fluid in the gate system, it can be designed to be heated in the section in any case (see heater 17).
The movement of the shut-off needle 3 is, for example, a direct or indirect (ie via an intermediately connected means) movement means, wherein a movable piston with a piston rod 20 fixed to the lifting plate 5 ( 19) with the aid of a fluid-operated drive cylinder 18 as drive device 6 . The drive device may also be embodied differently, for example an electric motor or an electromagnet or a hydraulic cylinder. It is also conceivable for the piston 19 to itself form a moving means to which the shut-off needle 3 is releasably attached.
It is also possible to attach a plurality of blocking needles 3 to the lifting plate 5 and still move the lifting plate 5 with only one drive device.
The shut-off needle 3 shown here is releasably engaged with the driving end 4 via an overload protection device, which is here as a (first) friction connection or friction inside and outside the moving means, here the lifting plate 5 . It is designed as a connecting portion 21 (see Fig. 2). The overload protection device is embodied in particular as follows: the shut-off needle 3 is connected directly or indirectly to the moving means, in particular the lifting means, via the at least one friction connection 21 which is releasable when the limiting force is exceeded. connected in the first direction of movement. In this case, the friction connection 21 is formed here according to an advantageous variant as a self-locking connection.
To this end, the at least one friction connection 21 is designed so that the shut-off needle is held rigidly and rigidly on the moving means in normal operation during the reciprocating movement of the moving means for opening and closing the needle valve nozzle 1 . Only in case of an overload exceeding the limiting force, the frictional force of the frictional connection 21 is overcome, so that the shut-off needle 3 and the end 4 of its movement are fitted in a tight fit (eg pin 23, sleeve) in the movement means. 24 and the second sleeve 28 ), so that the moving means can be moved in the X direction of the relative blocking needle 3 . Therefore, the overload protection function/device is implemented with simple design means.
In the following, various advantageous embodiments of the invention are considered in detail, the invention being not limited thereto.
In a first preferred variant, the moving means, in this case a lifting plate 5 , is pierced by a stepped bore 22 which may partly have a thread ( FIGS. 1 to 5 ). The driving end 4 of the blocking needle 3 is coupled to this bore 22 . In this case, the pin 23 is attached to the driving end 4 of the blocking needle 3 with the same axial extension. Also, the pin 23 can alternatively be formed integrally on the driving end 4 of the blocking needle 3 (see eg FIGS. 5A and 5B ).
The pin 23 has a conical outer shape, which is releasably held and secured directly through a friction fit in the conical bore 22'. To this end, the pin 23 is pressed with a predetermined force into the bore 22' during its assembly. The friction connection 21 is thus formed here by friction between the pin 23 with an outer cone A and a bore 22' with an inner cone I provided at least in part, and between the pin 23 and the bore 22'. (See Figures 5 and 6).
Preferably, the bore 22' is formed in at least one section of the inner cone in a manner corresponding to the conical shape of the pin 23 (see FIGS. 5 and 6 ). Here, the pin is narrowed from top to bottom, in the X direction, and the blocking needle 3 moves to the position of FIG. 1 c) in a closing operation.
Alternatively, the pin 23 may also be inserted directly into the bore 22 of the moving means, in particular the lifting plate 5 (not shown here, but similar to FIG. 5a ) or (not shown here). However, similar to Fig. 5a) or a component that is inserted into the moving means, in particular, it can be inserted into the lifting plate 5 (Figs. 2 to 4).
Preferably, this component may be a sleeve 24/(31). In a further preferred embodiment, the sleeve 24 may consist of a thread having an external thread, which is inserted into an internally threaded portion of the bore 22 , which itself is concentric with the internal bore 22 ′. ) can have The term “bore” is to be understood here and throughout this specification in the sense of an opening, in particular a through-hole, which need not necessarily be created by means of a drill.
In this case, the moving means 5 move the pin 23 in an axial linear manner in the X direction during a closing movement on the needle valve head 27 and the free end 4 of the shut-off needle 3 . ) is pressurized through
Both the pin 23 and the bore 22 or the bore 22' in the moving means, which are preferably concentric thereto in the component, in particular in the sleeve 24, are their in the X direction or at least in cross-section, respectively. It includes a corresponding outer cone (A) and an inner cone (I) over its entire length.
The pin 23 is assembled to the moving means 5, in this case via its outer cone A, in the sleeve 24 or to the inner cone I of the peripheral body (sleeve 24 or direct moving means). while being pressed with a defined force.
According to one variant, the shut-off needle 3 has an outer cone A instead of a separate pin 23 directly at one end thereof, and frictionally directly on the moving means 5 (or its sleeve 24 ). may be provided. Thus, the blocking needle 3 does not have a separate pin, but forms this pin by itself as its end. This variant is shown in FIG. 5 . Fig. 5 a) shows that the bore 22 in the lifting plate 5 is formed in a direct conical manner, and the driving end 4 of the shut-off needle 3 is formed in such a way that it corresponds to a pin-like conical form; 2 shows the components of an embodiment according to the principle.
In general, the pin 23 is frictionally engaged and self-locking to the peripheral body - preferably the sleeve 24 or the mold plate 5 - so that the translational movement of the moving means 5 is Move the blocking needle 3 in the pin and thus in the X direction or in the opposite direction -X direction. In this way, the closing needle 3 can move back and forth between a closed position (see, eg, FIG. 1B ) and an open position (eg, see FIG. 1C ).
During the closing movement in which the moving means (here the lifting plate 5) is moved in the -X direction, the closing needle 3 is placed on the pin 23 or the frictional engagement area between the inner cone (I) and the outer cone (A). Apply an axial force to If this axial force exceeds the static friction of the friction connection, the pin 23 is released from the peripheral body (preferably sleeve 24 or lifting plate 5) and the shut-off needle 3 is attached to the body or drive device. It is no longer moved in the closing direction -X.
In other words, this means that the pin 23 is triggered and no longer serves as an abutment for the blocking needle 3 . For example, this is shown in FIG. 2B . Here, the frictional connection 21 is released after moving the moving means (here, such a movement is not shown), and the blocking needle 3 can move relative to the moving means. Damage to the blocking needle 3 can be prevented in this way.
As a result of proper adjustment of the mounting force, the limiting force or threshold force at which the pin 23 is triggered can also be adjusted. In this way, the shut-off needle 3 is easily preserved from damage due to overload.
The moving means may be configured differently. This can be, for example, a piston directly or, for example, the lifting plate 5 described above. The lifting plate 5 (but not just the lifting plate) is preferably selected if at least one of the blocking needles is installed therein.
Optionally, a cover cap 26 may be positioned on the sleeve 24 at its end in a direction away from the shut-off needle 3 ( FIG. 2A ), which advantageously covers the bore 22 and releases the pin ( 23) from falling into the stroke volume of the lifting plate.
According to one variant, in relation to the other diameter of the shut-off needle 3 , the shut-off needle 3 at its end 4 lies axially on and/or fixed to the pin 23 . In the case of including the head 27 with a wider diameter, it is more advantageous that a good power transmission is ensured between the pin 23 and the shut-off needle 3 , especially if they are not integrally formed.
According to another optional further development, it is advantageously provided that the second sleeve 28 is inserted into the bore 22 under the sleeve 24 . This further sleeve 28 can be fixed between the shoulder of the stepped bore 22 of the moving means and the first sleeve 24 - in particular this sleeve 24 is formed with a screw. The second sleeve 28 itself preferably has a stepped inner bore 29 . In this case, the head 27 of the needle is movably guided in the inner bore 29 . In this case, it hits the collar of the inner bore 29 and cannot escape from the inner bore 29 . In general, the sizing is chosen such that the head 27 of the needle between the pin 23 and the collar of the stepped bore 29 has some play, so that the needle 3 avoids thermal stress. to move in a straight line in the main direction of movement X.
It is clearly shown in FIG. 2a that the pin 23 is pressed with its outer cone A into the inner cone of the sleeve 24 . The shut-off needle 3 is moved here in an upward direction (see FIG. 1c ) corresponding to the open position on the needle valve nozzle 1 . It is shown in FIG. 2b that the blocking needle 3 and the pin 23 have moved relative to the lifting plate 5 (the lifting movement is from the offset of the lifting plate 5 between FIGS. 2A and 2B of each stroke) can be seen in each case). The lifting plate 5 is moved in the downward direction. The shut-off needle 3 has an impeding force on it in a manner not appreciable here, which is greater than the press-in force for mounting the pin 23 on the moving means, in particular on the first sleeve 24 . Because it works, it did not follow these movements. The pin 23 has been released from its press fit/friction fit and does not follow the movement of the moving means.
The variants of Figures 3 and 4 differ from the variants of Figure 2 in that the overload protection device is designed to be triggered in both directions +X and -X.
For this purpose, the overload protection device advantageously has two (here locally separated) frictionally engaging connections 21a and 21b.
Structurally, this can be achieved in a variety of ways. According to the variant shown in FIGS. 3 and 4 , the (here, second phosphorus) screw sleeve 30 is inserted, in addition to the friction connection 21a, in this case in the lower part of the stepped bore 22 . This screw sleeve 30 is mounted on the side of the lifting plate 5 opposite the first sleeve 24 . The screw sleeve 30 has an inner cone I. An inner sleeve 31 is pressed into the core, which sleeve has an outer cone A. At the same time, this cone press-fit connection 21b tapers in the opposite direction (here, -x direction) as the first cone press-fit connection 21a.
The shut-off needle 3 passes through the inner sleeve 31 . This is in turn designed here such that the second sleeve 28 lies above it. Since the diameter of at least one or both of these components is greater than the inner diameter of the bore 32 of the inner sleeve 31 , the pin 23 and/or the head 27 moves downwardly from the lower sleeve 28 . Can't fall or get out
The function of the second friction connection 21b as part of the overload protection device is as follows:
The shut-off needle 3 has been displaced in the downward direction with the moving means in FIG. 4a , which here corresponds to the closed position of the needle valve nozzle 1 . When the shut-off needle 3 is moved from the closed position to the open position, the head 27 is supported against a lower annular collar of the second sleeve 28 so that the shut-off needle 3 is screwed therein. It is lifted together by the movement of the moving means together with the sleeves and the pins (23), (24), (28), (30), (31) to be inserted.
In FIG. 4b , the blocking needle 3 or head 27 , the second sleeve 28 and the inner sleeve 31 are shown moving relative to the lifting plate 5 . The lifting plate 5 has been moved in the upward direction. The shut-off needle 3 has such a movement, since a force acting on it acts thereon which is imperceptible here, which is greater than the pressing force for mounting the outer conical sleeve 31 with the means of movement, in particular the screw sleeve 30 . did not follow The externally conical inner sleeve 31 has been released from the press fit/friction fit on the mounting means, in particular the inner conical screw sleeve 30 , and does not follow the movement of the moving means.
According to FIGS. 5b and 5c , the two overload protection devices also operate in different directions when lifting or lowering the shut-off needle 3 with two cone press-fit connections 21a , 21b respectively. is implemented with However, the structural design is particularly simple, which is advantageous but not essential to the functioning of the present invention.
Also according to FIGS. 5b and 5c , either the conical driving end 4 or the conical pin 23 is inserted into the sleeve 31 having a bore 22 ′ formed conically with respect to the pin 23 . In this way, in turn, the cone press-fit connection 21a is implemented. The inner cone and outer cone expand in a first direction, “up” (-X direction). This corresponds to the first overload protection device according to FIG. 5a . The sleeve 31 therefore here also corresponds in each case to the sleeve 24 of FIGS. 2 to 4 .
However, in addition, the inner contour of the bore 22 and the outer contour of the sleeve 31 in the lifting plate 5 are designed in a corresponding conical shape. The inner cone and outer cone expand in a second direction, “down” (X direction). 5b and c, the bore 22 conically widens downward in the lifting plate X direction, so that the sleeve 31 can be released in an overloaded state from the friction fit of FIG. 5b in the downward direction. These are each a second overload protection device.
According to FIG. 5b the driving end 4 of the shut-off needle 3 can be integrally formed in a conical manner, thus forming the pin 23 itself. However, according to FIG. 5c , the pin 23 can be located at the driving end 4 (which is here formed as a cylindrical head 27 ).
This variant is structurally simple, but still works well.
As a result of the two friction connections according to FIGS. 3-5 , the overload protection device can reliably be triggered in each case of all possible directions of movement of the needle valve nozzle.

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Hereinafter, the operation mode of the overload protection device will be described in more detail with reference to FIGS. 6 and 7 again, which is structurally simplified, but shows a theoretically functional design.

During initial mounting, the conical pin 23 is pressed into the conical bore 22' of the sleeve 24 by means of a suitable device with a force F _M (see FIG. 6a ). As a result, a normal force F _N is formed via the side face (lateral angle α) of the cone of the conical friction connection. Friction (the constant μ = tanρ of friction) acts against the mounting force F _M and generates a friction force F _R . Therefore, the theoretically achievable normal force F _N(th) is reduced and the x component of the resultant force F _E is reduced to the remaining dispersion force F _S . As long as the y component F _{N (y)} of the normal force F _N is less than the y component F _{R (y} ) of the friction force F _R , there is self-locking and the conical pin can be pushed out again only by the releasing force F _L (see FIG. 6b ).

The force diagram in Fig. 7 shows that self-locking exists when:

The relationship of forces during the assembly and disassembly process is shown in FIG. 6B . The exact release force F _L is shown in FIG. 7 . For this purpose, if the mounting force F _M is removed, the direction of the friction force F _R is reversed, and since the x component F _R(x) of the friction force now corresponds to the dispersive force FS, the normal force F _N with the same dispersive force F _S is small Beware of losing The required release force F _L is mainly determined by the mounting force F _M , and depends on both the lateral angle α and the friction constant μ = tanρ as shown in the force diagram.

The influence of factors on release force (qualitatively) is shown in FIG. 7 . The following applies:

needle valve nozzle 1
closed end 2
blocking needle 3
drive end 4
lifting plate 5
drive unit 6
tool 7
Plates 8, 9, 10
Hot Runner Part 11
Hot Runner Flow Elements 12, 13, 14, 15
Melting Guide Channel 16
heater 17
drive cylinder 18
piston 19
piston rod 20
Friction connections 21, 21a, 21b
bore 22
bore 22'
pin 23
sleeve 24
cover cap 26
head 27
second sleeve 28
internal bore 29
screw sleeve 30
inner sleeve 31
bore 32
ejection volume 33
outer cone A
inner cone I
direction X
mold plate S
angle α
friction angle ρ
Mounting force FM
normal force FN
Friction force FR
resultant FE
dispersion force FS
release force FL
coefficient of friction μ

Claims (16)

A hot runner device having at least one needle valve nozzle (1) and a shut-off needle (3) movable by a moving means in the needle valve nozzle (1), and an overload protection device for the shut-off needle (3),
The overload protection device is characterized in that it is implemented as follows:
The blocking needle (3) is connected to the moving means directly or indirectly in at least one first direction of movement by means of at least one frictional connection (21a, 21b) which can be released when a limiting force is exceeded,
hot runner device.
According to claim 1,
The friction connection part (21a) is,
characterized in that it is designed with a self-locking connection,
hot runner device.
According to claim 1,
The friction connection part (21b) is,
characterized in that it is formed as a cross-press assembly,
hot runner device.
4. The method according to any one of claims 1 to 3,
characterized in that the overload protection device is based solely on the friction principle,
hot runner device
4. The method according to any one of claims 1 to 3,
The overload protection device is implemented as follows:
The blocking needle 3 is in each case directly or indirectly connected in two different directions of movement X; ) characterized in that it is connected to the moving means,
hot runner device.
4. The method according to any one of claims 1 to 3,
characterized in that one or both of the friction connections (21a, 21b) are implemented in each case by means of a releasable self-locking cone press-fit connection,
hot runner device.
7. The method of claim 6,
a first said releasable self-locking cone press-fit connection comprising:
as first friction partner an outer cone on the shut-off needle (3) or the abutment of the shut-off needle (3);
A second friction partner, characterized in that it is implemented by a bore of the moving means or an inner cone of a component inserted into the moving means,
hot runner device.
7. The method of claim 6,
the second releasable self-locking cone press-fit connection comprising:
an outer cone (A) on the sleeve (31) pierced by said shut-off needle (3) as first friction partner;
A second friction partner, characterized in that it is realized by an inner cone (I) in the moving means or in a further sleeve (30) inserted in the moving means,
hot runner device.
4. The method according to any one of claims 1 to 3,
the shut-off needle (3) can move linearly with the moving means in a direction (X) in a reciprocating manner,
characterized in that the shut-off needle (3) is only frictionally connected to the moving means in said direction (X) and/or opposite said direction (X),
hot runner device.
4. The method according to any one of claims 1 to 3,
Characterized in that the moving means comprise a lifting plate (5) movable by means of a drive device,
hot runner device.
7. The method of claim 6,
one or both of the friction and/or self-locking connections are
The blocking needle 3 or the junction of the blocking needle 3 is frictionally coupled to the moving means and connected in a self-locking manner,
characterized in that the shut-off needle (3) is embodied to release automatically upon introduction of an axial force exceeding the self-locking and greater than the static friction of the friction connection,
hot runner device.
4. The method according to any one of claims 1 to 3,
before exceeding the above limit,
characterized in that by not allowing elastic deformation while the frictional engagement by the at least one frictional connection (21a, 21b) is released, axial displacement of the blocking needle (3) does not occur,
hot runner device.
4. The method according to any one of claims 1 to 3,
characterized in that the blocking needle (3) comprises a cylindrical head,
hot runner device.
4. The method of claim 2 or 3,
The limiting force is
characterized in that it is lower than the consumed mounting force,
hot runner device.
15. The method of claim 14,
The level of the limiting force is
dependent on the level of the mounting force, characterized in that the adjustment of the constraining force is through the mounting force,
hot runner device.
4. The method of claim 3,
wherein the cross-press assembly is formed as a retract, stretch and/or stretch-retract assembly,
hot runner device.

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